I use the Bessa-T with three finders, a CV50 1:1 finder, a CV25 finder, and for other focal lengths a 35-135 zoom finder.
The biggest drawback with the zoom finder is that it's large and heavy. Because of that weight and size and the location of the strap lugs on the T, it makes the camera tilt backwards when it's hanging on the neckstrap. Quite distracting when you're walking around..
It balances best with the (smallest) CV 50 finder. Possibly also because the 50 serves as a proper counter weight, while the 25 and 35 I have are light and compact..